What is the best manual transmission fluid?

Freedom through Jesus

So I know the manual says to use plain old 5w-30, I believe I used Redline last time I replaced the fluid, I've heard of Amsoil and GM Syncromesh (amongst others...), has anyone found any benefit to any of these over just a couple cheap bottles of motor oil? I wasn't impressed by Redline, still feels notchy, could be a mechanical thing more so than a fluid thing, just wanted to share my experience.

So what do you prefer and why? Any science/data to back up your position?

Thanks!

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New Member

I recently put in Penzoil Synchromesh in my 2000 GS-R. It just replaced the Honda MTF2. The car just had fresh Honda MTF2 put in a couple months ago by the dealer just before I bought the car. I do prefer the shift feel of Synchromesh over the Honda MTF2. The Honda MTF2 that is sold nowadays is on the thin side, in line with a 20 weight oil or an ATF. The original Honda MTF1 that was developed back in the 90's and recommended for our cars was a thicker fluid (more like a 30 weight fluid).

My favourite fluid is Amsoil MTF but I just couldn't find it on short notice in my region as my local performance shop stopped selling Amsoil fluids. When I get time in the off-season I may switch to Amsoil MTF as it was my favourite in my S2000 and should work well in the Integra. I am liking the Sychromesh right now though and would recommend it over the Honda MTF. Redline MTL is a great fluid but for some reason I always found it notchy in Hondas, it seemed to work well in hot temp use but it was notchy when used in cooler weather. I think Amsoil MTF is the best fluid, followed by Pennzoil Synchromesh.

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New Member

my only complaint with the current Honda MTF2 is that it starts out very thin, and then shears down quickly with the meshing action of the gears so it just gets thinner over time. Change it out frequently and it works good, and good for cold weather use being on the thinner side.